CVE-2026-41882: IntelliJ IDEA Path Traversal Vulnerability

CVE-2026-41882 Overview

CVE-2026-41882 is a Local File Inclusion (LFI) vulnerability affecting JetBrains IntelliJ IDEA that allows attackers to read arbitrary local files through the IDE's built-in web server. This vulnerability is classified under CWE-59 (Improper Link Resolution Before File Access), indicating the application fails to properly validate file path references before accessing local resources.

The built-in web server in IntelliJ IDEA, designed to facilitate local development and debugging workflows, can be exploited by remote attackers to access sensitive files on the developer's workstation. This could expose source code, credentials, configuration files, and other sensitive data stored locally.

Critical Impact
Attackers can remotely read arbitrary local files from developer workstations, potentially exposing source code, API keys, credentials, and sensitive configuration data through IntelliJ IDEA's built-in web server.

Affected Products

JetBrains IntelliJ IDEA versions before 2024.3.7.1
JetBrains IntelliJ IDEA versions before 2025.1.7.1
JetBrains IntelliJ IDEA versions before 2025.2.6.2
JetBrains IntelliJ IDEA versions before 2025.3.4.1
JetBrains IntelliJ IDEA versions before 2026.1.1

Discovery Timeline

2026-04-30 - CVE-2026-41882 published to NVD
2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-41882

Vulnerability Analysis

This vulnerability exploits the built-in web server functionality present in JetBrains IntelliJ IDEA. The IDE includes a local web server that runs by default to support features like live editing, debugging, and previewing web content during development. The vulnerability allows an attacker to craft specially designed requests that bypass file access controls and read arbitrary files from the local file system.

The attack requires user interaction (such as visiting a malicious website or clicking a crafted link) while the IDE is running with the web server active. When successfully exploited, the attacker gains read access to any file accessible by the user running IntelliJ IDEA, which typically includes sensitive development artifacts, credentials, and configuration files.

Root Cause

The root cause stems from improper link resolution and insufficient path validation in the built-in web server's file serving mechanism. Classified under CWE-59 (Improper Link Resolution Before File Access), the vulnerability occurs when the web server fails to properly sanitize or validate file path requests, allowing attackers to traverse outside intended directories and access arbitrary local files.

The web server component does not adequately validate that requested resources are within the expected webroot or project directory, enabling path traversal techniques to access files anywhere on the file system that the IDE process has permission to read.

Attack Vector

The attack is network-based and requires no prior authentication, but does require user interaction. An attacker can exploit this vulnerability by:

Crafting a malicious web page or link that makes requests to the IntelliJ IDEA built-in web server
Tricking a developer into visiting the malicious page while IntelliJ IDEA is running
The malicious requests leverage improper path handling to read arbitrary local files
File contents are exfiltrated back to the attacker's server

The attack surface is significant as the built-in web server is commonly enabled during development activities, and developers frequently browse the web while their IDE is active. The exploitation could target sensitive files such as .env files, SSH keys, AWS credentials, database connection strings, or proprietary source code.

Detection Methods for CVE-2026-41882

Indicators of Compromise

Unusual network connections from the IntelliJ IDEA process to external IP addresses
Unexpected file access patterns in system audit logs showing reads of sensitive files outside project directories
Web server access logs showing requests with path traversal sequences (e.g., ../, encoded variants)
Network traffic anomalies on the default IntelliJ IDEA web server port (typically port 63342)

Detection Strategies

Monitor network traffic from IDE processes for suspicious outbound connections or data exfiltration patterns
Implement endpoint detection rules to alert on path traversal attempts targeting the IntelliJ IDEA built-in web server
Review process-level file access monitoring for IntelliJ IDEA accessing files outside expected project directories
Deploy web application firewall rules to detect and block path traversal patterns in local web server requests

Monitoring Recommendations

Enable audit logging for file access events on developer workstations, particularly for sensitive directories
Configure network monitoring to track connections to and from IntelliJ IDEA's built-in web server
Implement alerting for unusual volumes of file read operations originating from IDE processes
Consider deploying browser security extensions that restrict cross-origin requests to localhost services

How to Mitigate CVE-2026-41882

Immediate Actions Required

Update JetBrains IntelliJ IDEA to the latest patched version immediately (2024.3.7.1, 2025.1.7.1, 2025.2.6.2, 2025.3.4.1, or 2026.1.1 depending on your version branch)
Review and restrict network access to the built-in web server if not actively needed for development
Audit developer workstations for any signs of unauthorized file access or data exfiltration
Consider temporarily disabling the built-in web server until patching is complete

Patch Information

JetBrains has released security updates addressing this vulnerability. Refer to the JetBrains Security Issues Fixed page for official patch information and release notes. Users should update to one of the following patched versions based on their release branch:

Version 2024.3.7.1 or later for the 2024.3.x branch
Version 2025.1.7.1 or later for the 2025.1.x branch
Version 2025.2.6.2 or later for the 2025.2.x branch
Version 2025.3.4.1 or later for the 2025.3.x branch
Version 2026.1.1 or later for the 2026.1.x branch

Workarounds

Disable the built-in web server feature in IntelliJ IDEA settings if it is not required for your development workflow
Configure firewall rules to block external access to the IntelliJ IDEA web server port (default 63342)
Use browser isolation or sandboxing when browsing untrusted websites while the IDE is running
Implement network segmentation to limit the potential impact of data exfiltration from developer workstations

bash

# Firewall configuration to restrict IntelliJ IDEA web server access (Linux/iptables example)
# Block external connections to default IntelliJ web server port
sudo iptables -A INPUT -p tcp --dport 63342 -s 127.0.0.1 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 63342 -j DROP